Liquid-crystal lenses with variable refractive index have heretofore been proposed. Liquid-crystal lenses are being demanded to decrease the drive voltage. In view of this, for example, Patent Literature 1 proposes a liquid-crystal lens in which a transparent insulating layer is interposed between an electrode and a liquid crystal layer and a high-resistivity layer is disposed on a surface of the transparent insulating layer facing the liquid crystal layer. With the provision of a high-resistivity layer as described in Patent Literature 1, the drive voltage of the liquid-crystal lens can be decreased.